The present invention relates to helical cutters. More particularly, the present invention relates to improvements of helical cutters of the type disclosed in the John S. Stewart U.S. Pat. Nos. 5,603,365 and 5,738,156, the disclosures of which are incorporated herein by reference.
The Stewart U.S. Pat. Nos. 5,603,365 and 5,738,156 and the prior art references cited therein, are incorporated herein for the purposes of teaching the nature of such helical cutter heads, the mounting of inserts in helical arrangements on such cutter heads, and the specifically disclosed cutters or blade units. Reference is made to FIG. 5 in U.S. Pat. No. 5,603,365, for example, which shows a triangular shaped cutter or blade unit 24 having a cutting edge 38 formed on a raised portion 39 along one edge. The blade unit has sides 32 which engage or butt against the flat raised portions 30 of the triangular cavities or recesses in the cutter. As pointed out in these prior patents, the blade unit 24 may be made from materials selected from the group consisting of diamond, ceramic, carbide, high cobalt alloys, and high speed steel. The cylindrical cutter or the cutter head inserts disclosed in U.S. Pat. No. 5,603,365 may be made from ordinary steel which is relatively easier to fabricate. FIGS. 5 and 6 of U.S. Pat. No. 5,738,156 show a preferred structure in which individual blade units 24 are mounted directly into triangular recesses formed in helical patterns on the cylindrical cutter.
It has been determined that very significant and substantial increases in repeatability are obtained by having one of the two sides 32 mount against one point while the other side 32 mounts against two-points. The blade unit 24 is provided with a smooth, flat bottom which slides on a smooth flat recess surface. The three-point contact on the sides 32 of the blade unit 24 gives accuracy and repeatability in positioning. This three-point mounting system removes the variability of the cutters 24 which are typically provided by a vendor of carbide blades. Even with typical variability, the three-point mounting of the present invention works accurately to position the blade units.
While a three-point mounting with a triangular blade, such as the blade 24, is preferable, it will be appreciated that blades having different shapes may be positioned against three spaced-apart points accurately to position the blades in helically disposed recesses. Preferably, the cutter will be machined or otherwise formed to have recesses providing flat, upwardly facing surfaces for receiving blade units having flat, smooth bottoms to slide on such surface with the blade unit abutting the three-points.
While the structure shown in Stewart U.S. Pat. Nos. 5,603,365 and 5,738,156 have been found to be very good structures, the present invention provides spectacular structures with a significant increase in the ability to produce a high quality cutter head which is consistently repeatable. It will be appreciated from the disclosure of the prior U.S. Pat. Nos. 5,603,365 and 5,738,156 that the present invention provides a helical cutting edge about a cylindrical cutter with the edge being provided by a plurality of triangular blade units received in helically arranged recesses. The present invention improves the mounting of the triangular blade units by mounting the sides 32 against three-points, rather than against two flat surfaces, as taught by U.S. Pat. Nos. 5,603,365 and 5,738,156, as well as provide greater accuracy and repeatability in positioning.
Accordingly, the present invention provides a cutter head for an industrial woodworking machine, the cutter head including a generally cylindrical portion, a plurality of circumferential, spaced grooves extending into the cutter head body from the periphery of the cylindrical portion. The grooves include a plurality of blade unit mounting cavities. Each of the blade unit mounting cavities comprises a hole and spaced-apart mounting points. The hole receives a fastener to removably secure a blade unit in each of the mounting cavities. Each blade unit comprises at least one blade edge and is configured to have the blade edge disposed to align with the blade edges of other blade units in other mounting cavities. This forms a substantially helical blade when each blade unit is secured adjacent at least one of the spaced-apart mounting points.
The cutter head may also provide a helical series of triangular pockets formed therein with each pocket having two inwardly facing walls, a mounting point on one wall and two mounting points on the other wall to provide three spaced mounting points. In addition, each pocket has a hole to receive a fastener to secure the blade unit. Furthermore, the blade unit is triangular with a flat, smooth bottom, a blade edge and two sides and configured to have the blade edge disposed to align with another blade unit in other mounting cavities. This forms a substantially helical blade when each blade unit is secured to its mounting cavity in a cutter head, when seated in the triangular pocket with said sides abutting the mounting points.
A method of changing blades in a cutter head for an industrial woodworking machine may be provided. The cutter head includes a generally cylindrical portion, a plurality of circumferential and spaced grooves extending into the cutter head body from the periphery of the cylindrical portion. The grooves include a plurality of removable blade unit mounting cavities adapted to receive removable blade units. The method comprises removing blade units from the blade unit mounting cavities, including loosening fasteners securing the blade units to the blade unit mounting cavities. The method also includes mounting replacement blade units in the blade unit mounting cavities by inserting blade units into the blade unit mounting cavities, and urging faces of each of the blade units against positioning points of each of the mounting cavities. The screws are then tightened by securing the blade units to the blade unit mounting cavities forming a substantially helical blade made up of blade units secured to the cutter head.
Another method of changing blades in a cutter head for an industrial woodworking machine comprises removing blade units from the blade unit mounting cavities, and mounting replacement blade units in the blade unit mounting cavities to be against three separate mounting points provided by each cavity.
Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.